Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
H, W = map(int, input().split())
con = [[1,0],[0,1],[-1,0],[0,-1]]
m=[]
c = 0
d = [[0]*(W+2) for _ in range(H+2)]
d[1][1]= 1
m.append("#"*(W+2))
for i in range(H):
    b = input()
    c +=b.count(".")
    a= "#"+b+"#"
    m.append(a)
q = deque()
m.append("#"*(W+2))
q.append((1,1))

while len(q)>0:
    y,x = q.popleft()
    if y == H and x == W:
        print(c-d[H][W])
        exit()
    for dx,dy in con:
        #print(y+dy,x+dx,d[y+dy][x+dx])
        if d[y+dy][x+dx] == 0 and m[y+dy][x+dx] ==".":
            q.append((y+dy,x+dx))
            d[y+dy][x+dx]+=d[y][x]+1
    #print(q)
print(-1)